The present invention is directed to systems and methods for scanning documents. More specifically, without limitation, in one embodiment, the present invention relates to systems and methods that employ a plurality of imaging elements that can capture an upward facing document under normal illumination, process plural images, correct for geometrical and other forms of distortions, and reconstruct the image for scanning, displaying, copying, distributing, and storage.
Traditional scanning or copying systems require the document to be placed upside down on a transparent platform. Under the platform, a special illumination system illuminates lines or portions of the document sequentially while imagers or light sensors capture the reflected light to form an undistorted and balanced image of the document. The use of motion components to facilitate the scanning process often hinders performance and adds to both the initial cost and maintenance cost of the system. The traditional design renders use of scanning and copying equipment counterintuitive and inconvenient to use. For example, when a user needs to copy from a thick bound volume of a journal, the user may need to turn the volume upside down and apply sufficient forces with both hands so that the central margins of the pages lie as flat as possible and are therefore not severely distorted and defocused. This process may also create stress and damage to the volume.
These and other disadvantages of known techniques are solved in one embodiment of the present invention by the use of an opto-mechanical imaging system employing multiple imaging elements in conjunction with image processing algorithms. For example, when a user reads a document such as a book, the imaging element array can capture the images of opened pages of the book and processes the images to reconstruct the image to ideal format and clarity. The user need only turn the pages and command the scanning or copying with the disclosed system. The disclosed system may be combined with a system for displaying or printing.
The rapid development of image sensors built using newer technologies such as CCD and CMOS technologies has led to digital sensors that are orders of magnitude more sensitive. Additionally, these sensors are relatively inexpensive, particularly when manufactured in high volume. High-performance hardware to facilitate post-processing has also become inexpensive.
Systems that employ a “camera-like” setup to capture a document such as a bound book for scanning and copying have been the subject of at least one U.S. Patent (U.S. Pat. No. 5,969,795 to Honda). However, one embodiment of the present invention discloses an innovative scheme that employs a plurality of imagers, image processing algorithms, and processing hardware in such a way that a high-quality, high-performance, yet inexpensive, easy to use device can be made to scan or copy a document face-up.